Objectives This prospective study aimed to examine if sleep duration is a risk indicator for ischemic heart disease (IHD) and all-cause mortality, and how perceived stress during work and leisure time and use of tranquilizers/hypnotics modifies the association.

Method A 30-year follow-up study was carried out in the Copenhagen Male Study comprising 5249 men (40–59 years old). Confounders included lifestyle factors (smoking, alcohol, and leisure-time physical activity), clinical and health-related factors (body mass index, blood pressure, diabetes, hypertension, and physical fitness) and social class. Men with a history of cardiovascular disease at baseline were excluded.

Results During follow-up, 587 men (11.9%) died from IHD and 2663 (53.9%) due to all-cause mortality. There were 276 short (<6 hours), 3837 medium (6–7 hours), and 828 long (≥8 hours) sleepers. Men who slept <6 hours had an increased risk of IHD mortality but not all-cause mortality, when referencing medium sleepers. Perceived psychological pressure during work and leisure was not a significant effect modifier for the association between sleep duration and IHD mortality. In contrast, among men using tranquilizers/hypnotics (rarely or regularly), short sleepers had a two-to-three fold increased risk of IHD mortality compared to medium sleepers. Among those never using tranquilizers/hypnotics, no association was observed between sleep duration and IHD mortality.

Conclusion Short sleep duration is a risk factor for IHD mortality among middle-aged and elderly men, particularly those using tranquilizers/hypnotics on a regular or even a rare basis, but not among men not using tranquilizers/hypnotics.